When a physician or healthcare provider initially suspects that a patient has had a stroke, the physician will undertake a number of steps to verify the diagnosis. In initially diagnosing whether the patient has suffered a hemorrhagic or an ischemic stroke, the physician may have initially completed brain imaging using an image scanner. This initial high level diagnosis is important in considering treatment options and in particular whether or not to administer thrombolytic drugs, which may be referred to as a clot dissolving or busting drug. Until recently, the thrombolytic drug referred to as a pharmacological tissue plasminogen activator (tPA) has been the only non-surgical standard of care for treating patients with acute ischemic stroke. There are several different types of tPA which is a recombinant human protein. Alteplase is the generic name of the marketed version of tPA that is used to treat stroke. As is known, tPA works by breaking up the thrombus or blood clot blocking blood flow to the brain that had caused the stroke. While this non-surgical treatment is highly effective in many scenarios, the drug may not succeed in dissolving the thrombus when the thrombus itself is either too large and/or the thrombus does not have the porosity to enable effective and timely penetration of the drug within the thrombus. In addition, tPA cannot be given to people who are taking blood thinners or have had recent surgery or have another of several medical contraindications to thrombolytic therapy.
It is in this context that recent stroke trials have shown efficacy of another treatment, namely the use of various endovascular techniques and specifically, the use of catheter systems to remove a thrombus from within the brain arteries. Endovascular therapy is highly efficacious, however it entails a very high level of expertise from the surgical teams as well as the supporting infrastructure. As such, it is limited to a relatively small number of tertiary care hospitals across the world.
As a result, given the generally resource intensive nature of endovascular therapy and the required skill levels of the physicians, these procedures may generally only be available in a relatively low number of large hospitals.
Stroke, however, is a common disease with a wide range of severity. That is, minor strokes may require no treatment whereas non-fatal severe strokes can result in a wide range of outcomes for the patient and a wide range of disabilities. As such, the ultimate outcome of the patient can be affected by a number of factors.
Importantly, many stroke patients will be taken to hospitals near their community where endovascular therapy is unavailable. Some of these patients may benefit from thrombolytic drugs (e.g. alteplase), while others may need to be transferred to a larger tertiary hospital in order to benefit from endovascular therapy.
Decisions on whether to transfer patients need to be made quickly, as every minute counts in cases where endovascular therapy is the preferred treatment. That is, in a typical acute ischemic stroke case where affected areas of the brain are at risk of dying, every minute until reperfusion the brain loses on average of 1.9 million neurons, 14 billion synapses and 7.5 miles of myelinated fibers. On the other hand, in cases where affected areas of the brain are already irreversibly infarcted, decisions have to be appropriate and correct to avoid patients being transferred to larger hospitals where endovascular therapy is unlikely to produce a better outcome for the patient.
Currently, the expertise needed to make these triaging decisions is unavailable in community hospitals. As a result, physicians in these community hospitals may make decisions that result in significant costs in unnecessarily transferring patients to larger centers and incurring additional diagnostic and treatment costs at these larger centers when the treatment outcome is unlikely to have been improved. On the other hand valuable time may be lost in decision-making and other delays in transfer of patients at the community hospitals who may actually benefit from the transfer to a tertiary care hospital for endovascular thrombectomy.